1. Field
The invention relates to wireless communications. More particularly, the invention relates to methods and apparatus for resolving transmission priority in a wireless peer-to-peer network.
2. Background
Wireless communications continues to grow in demand and has become an integral part of both personal and business communications. Wireless communications allow users to transmit and receive data from most anywhere using wireless networks and wireless devices such as laptops, cellular devices, iPhones®, BlackBerrys®, etc.
WiFi describes the wireless networks that adhere to the specifications developed by the Institute of Electrical and Electronic Engineers (IEEE) for wireless local area networks (LAN). WiFi devices are certified to be interoperable with other certified WiFi devices using the 802.11 standard of the IEEE. These WiFi devices allow over-the-air interfaces in order to create a wireless network for facilitating data transfer.
Generally, wireless networks are established through mobile devices communicating with one or more base stations, access points or access routers. A base station is a radio receiver/transmitter that serves as a hub for wireless networks. A base station can act as a relay for devices that are connected to it. An access router may be configured as an access point that covers a geographic range or cell and, as the mobile device is operated, it may move in and out of these geographic cells.
Some wireless networks can be constructed utilizing solely peer-to-peer communications without utilizing base stations, access points, or access routers. Such wireless networks are sometimes referred to as ad hoc networks. Communications in such networks may, in some cases, be limited to exchanges between mobile devices that are within direct wireless transmission range of each other, while in other cases multi-hop forwarding between non-adjacent mobile devices may be supported. Various techniques may be used to maintain connectivity and/or forward information as the topology of the wireless network changes (e.g., as mobile devices join the network, leave the network, or move within the network). Some networks can also be constructed utilizing a combination of peer-to-peer communications as well as communications with base stations, access points, or access routers.
In a time slotted ad-hoc wireless network with a designated phase for medium access contention (e.g., the connection scheduling phase in FlashLinQ), links contend simultaneously for a channel based on a notion of link priority. The notion of priority within a link needs to be resolved to resolve which of the two nodes within a link has the priority to transmit (“transmission priority”). In many cases, the nodes are half-duplex (i.e., cannot transmit and receive at the same time). Thus, a signaling protocol to determine the transmitter and the receiver of data between the two ends of the link is needed.
In FlashLinQ, as an example, a Txp stage within connection scheduling was designed so that a node with a transmission priority shows its intention to transmit during a transmit priority (Txp) so that the other node sharing the same link can determine whether or not it can contend as a transmitter in the current slot. A feature of the current protocol is that the Txp always appears together with an initiator request (Tx). This is simply due to the fact that after a Txp is sent, it is always followed by a Tx. As a consequence, some information can be sent over the combination of the signals in Tx_P and Tx. For example, the information can be conveyed by the phase difference between the Tx_P and Tx signals. One example of such information is the quality of service (QoS) information of the current transmission request. Since only the transmitters send out this information, this causes an asymmetry between the transmitter side and the receiver side (i.e., there is no similar mechanism to feedback this information from the receivers to the transmitters).
Therefore, it has been recognized by those skilled in the art that a need exists for methods and apparatus for resolving transmission priority in wireless peer-to-peer networks where there is symmetry between the transmitter side and the receiver side.